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Red Crossbill, percna subspecies

APPENDIX 1

Threat Classification Table

StressThreata Causal certaintyb TimingFrequency Extent Severityb Level of concernb
Local Range-wide Local Range-wide
Reduced population

C: Habitat loss or degradation

G: Habitat disease

S: White pine blister rust

/ Scleroderris canker

Medium Medium Historic/ currentContinuousWidespread High (1) High High
Reduced population

C: Habitat loss or degradation

G: Fire

S: Forest fire

High Low Historic/ current Recurrent Localized High Low Low
Reduced population

C: Habitat loss or degradation

G: Insects

S: Tree loss

High (2)Medium (2) Historic/ currentContinuousWidespread HighUnknown (3) Medium
Reduced population

C: Exotic species

G: Food competition

S: Red squirrels

Medium (5)Medium (5) CurrentContinuousWidespreadUnknown Unknown Medium
Reduced population

C: Natural processes

G: Nest predation

S: Interspecific nest predation

(jays and squirrels)

Low Low Current SeasonalWidespreadUnknown Unknown Low
Reduced population

C: Habitat loss or degradation

G: Fire suppression

S: Forest conversion

High Low Current/ anticipated Seasonal Localized High Low Low
Reduced population

C: Habitat loss or degradation

G: Spruce budworm

S: Reduced cone production

High High Historic/ anticipated One-timeWidespread High (4) High (4) High
Reduced population

C: Habitat loss or degradation

G: Loss of forest cover

S: Urbanization

Medium Low Current/ anticipatedContinuous Localized Medium Low Low
Reduced population

C: Habitat loss or degradation

G: Loss of forest cover

S: Agricultural expansion

Medium Low Current/ anticipatedContinuous Localized Medium Low Low
Reduced population

C: Habitat loss or degradation

G: Forestry

S: Commercial harvest

High Low (6) Historic/ currentContinuousWidespread High Unknown High
Reduced population

C: Habitat loss or degradation

G: Forestry

S: Domestic harvest

Medium Low Historic/ currentContinuousWidespread Medium Low Low
Reduced population

C: Natural processes

G: Not applicable

S: Allee effect

Low Low Current/ anticipatedContinuousWidespreadUnknown UnknownMedium (7)
Reduced population

C: Natural processes

G: Interspecific competition

S: Seed-eating finches

Low Low Current/ anticipatedContinuousWidespreadUnknown UnknownMedium (7)
Cumulative effects

All, some,

or many of the above

 

a   C = threat category; G = general threat; S = specific threat.

b   Qualifiers:          

1 – High if eastern white pine is deemed important.

2 – This may need to be revisited if an insect is discovered to impact red pine.

3 – Severity is dependent upon the effectiveness of monitoring and control programs.

4 – Dependent upon Red Crossbill food preference.

5 – In areas of black spruce.

6 – Dependent upon forestry statistics to indicate management practices of forests to ensure perpetual availability of viable habitat for Red Crossbills.

7 – Level may change if research indicates that there is an increased level of importance for this threat.


APPENDIX 1.1

Clarification of terms used in Threat Classification Table. [1] 

Potential threat categories:

  • Habitat loss or degradation
  • Consumptive use
  • Pollution
  • Exotic species
  • Modification of natural processes
  • Changes in ecological dynamics
  • Accidental mortality
  • Disturbance and persecution
  • Climate and natural disasters
  • Natural processes and activities

Potential causal certainty categories:

  • High – Evidence causally links the threat to stresses on population viability.
  • Medium – The correlation between the threat and population viability is derived from expert opinion.
  • Low – Considered a putative or plausible threat only.

Potential timing categories:

  • Historic – Likely contributed to population declines, but is no longer affecting the species.
  • Current – Is likely affecting the species at the present time.
  • Imminent – Is expected to affect the species in the near future unless mitigation is undertaken.
  • Anticipated – May affect the species in the future.
  • Unknown – Unknown if factor has affected or will affect the species.

Potential frequency categories:

  • One-time occurrence
  • Seasonal – Either because the species is migratory or the threat occurs only at certain times of the year
  • Continuous – Ongoing
  • Unknown

Potential severity categories:

  • High – Very large population effect expected.
  • Medium – Intermediate population effect expected.
  • Low – Very low population effect expected.



[1]The list of categories below is representative of all potential categories.  Not all categories listed below are used in the table.